The goals of this research are to delineate the nature of, the structure of and the molecular motion in thermotropic and lyotropic liquid crystals using pulsed nuclear magnetic resonance techniques. The intermolecular and intramolecular contributions to proton relaxation in nematic liquid crystals will be studied using isotopic dilution and frequency dependence of relaxation. Cholesteric liquid crystals will be studied to determine the effect on molecular motion caused by the presence of unsaturated ester groups. Model membrane bilayer systems (smectic phase lyotropic liquid crystals), such as lecithin/water, will be investigated using pulsed nuclear magnetic resonance and Raman spectroscopy. Oriented samples will be utilized to minimize proton dipolar interactions and permit the use of spin echo techniques. Of particular interest will be the diffusion of the membrane molecules in the bilayer and the diffusion of water along and through the bilayer. The physical characteristics of the thermal phase transition which occurs in the bilayers will also be studied.